(a) Field of the Invention
The present invention relates to a liquid crystal display, and more particularly, to a vertically-aligned liquid crystal display in which pixel regions are divided into small domains.
(b) Description of the Related Art
In a liquid crystal display (LCD), liquid crystal material is injected between an upper substrate, on which common electrodes and a color filter are formed, and a lower substrate, on which thin film transistors and pixel electrodes are formed. A voltage of a different potential is applied to the pixel electrodes and common electrodes to form an electric field, thereby varying the alignment of liquid crystal molecules of the liquid crystal material. In this way, the transmittance of incident light is controlled to enable the display of images.
However, a serious drawback of LCDs is the limited viewing angle. Various methods and configurations have been developed to overcome this problem. Among such methods, the liquid crystal molecules are aligned perpendicularly to the upper and lower substrates, and either a predetermined aperture pattern or protrusions are formed on the pixel electrodes and the opposing common electrodes.
By forming the aperture patterns on the pixel electrodes and common electrodes, a fringe field is generated. Using the fringe field, a slanting direction of the liquid crystal molecules is controlled to increase the viewing angle. When protrusions are formed on the pixel electrodes and common electrodes, on the other hand, an electric field distorted by the protrusions is used to control the slanting direction of the liquid crystal molecules. In an alternative method, aperture patterns are formed in the pixel electrodes provided on the lower substrate and protrusions are formed on the common electrodes provided on the upper substrate. Using a fringe field generated by the aperture pattern and protrusions, the slanting direction of the liquid crystal molecules is controlled to form domains.
However, in the above methods, dark portions where light is not transmitted appear in areas where the aperture patterns and protrusions are formed. As a result, a large area occupied by the aperture patterns and protrusions may reduce the brightness of the LCD panel. If the number of aperture patterns and protrusions is reduced in an attempt to remedy this problem, the ability to control the slanting of the liquid crystal molecules is reduced and results in an uneven alignment. Hence, the texture generated by the uneven alignment extends over relatively large areas and reduce the brightness and overall picture quality.
The present invention has been made in an effort to solve the above problems.
It is an object of the present invention to provide a liquid crystal display in which spacing between aperture patterns, protrusions and other such elements that control the formation of domains is controlled to optimize the size of domains and enhance the picture quality.
To achieve the above object, the present invention provides a liquid crystal display comprising first and second substrates provided opposing one another; a liquid crystal layer made of liquid crystal material injected between the first and second substrates; pixel electrodes and a common electrode formed on at least one of the substrates, the pixel electrodes and common electrode generating an electric field that acts on the liquid crystal layer; and domain formation means for controlling a slanting direction of liquid crystal molecules within the liquid crystal layer, wherein m is an integer satisfying the following:
h/2(xcfx80/wp)xc2xdxe2x88x922xe2x89xa6mxe2x89xa6h/2(xcfx80/wp)xc2xd+2
where m is a number of domains formed by dividing the pixel electrodes by the domain formation means, w is a length of a first direction of the pixel electrodes, h is a length of a second direction of the pixel electrodes, the second direction being perpendicular to the first direction, and p is a width of a second direction of the domain formation means.
In another aspect, the present invention provides a liquid crystal display comprising first and second substrates provided opposing one another; a liquid crystal layer made of liquid crystal material that is injected between the first and second substrates; pixel electrodes and a common electrode formed on at least one of the substrates, the pixel electrodes and common electrode generating an electric field that acts on the liquid crystal layer; and domain formation means for controlling a slanting direction of liquid crystal molecules within the liquid crystal layer, wherein the domain formation means includes first direction means and second direction means according to an alignment direction, and wherein the pixel electrodes are divided into a first region corresponding to a position of the first direction means and a second region corresponding to a position of the second direction means, and wherein m is an integer satisfying the following:
h/2(xcfx80/wp)xc2xdxe2x88x922xe2x89xa6mxe2x89xa6h/2(xcfx80/wp)xc2xd+2
where m is a number of domains formed by divisions into the first regions and second regions respectively by the first direction means and second direction means, w is a length of a first direction of the first regions and a length of a second direction of the second regions, h is a length of a second direction of the first regions and a first direction of the second regions, and p is a width of the second direction of the first direction means and a width of the first direction of the second direction means.
According to a feature of the present invention, the domain formation means is realized through first and second aperture patterns formed respectively in the common electrode and the pixel electrodes.
According to another feature of the present invention, the first aperture pattern and the second aperture pattern are formed alternately.
According to yet another feature of the present invention, the domain formation means is realized through first and second protrusions formed respectively on the first and second substrates.
According to still yet another feature of the present invention, the first protrusions and the second protrusions are arranged alternately.
According to still yet another feature of the present invention, the domain formation means is realized through an aperture pattern formed in the pixel electrodes and protrusions formed on the first substrate.
According to still yet another feature of the present invention, apertures of the aperture pattern and the protrusions are arranged alternately.
According to still yet another feature of the present invention, h=3w and p=w/10.
According to still yet another feature of the present invention, h=1.5w and p=w/10.
According to still yet another feature of the present invention, if a length of a direction vertical to liquid crystal directors of the domains divided by the domain formation means is denoted by xcex1, and a length of a direction parallel to the liquid crystal directors of the domains is denoted by xcex2, xcex2/xcex1xe2x89xa6⅓.